Thermodilution is a method of determining blood flow through a body vessel based on in vivo measurements of temperature drop of blood using a temperature sensor as a result of introducing an indicator fluid (e.g., saline) having a lower temperature than blood into the blood upstream from the temperature sensor. The measured temperature drop, which is a function of the blood flow and set indicator fluid flow, may be used to determine the absolute blood flow rate through the body vessel. The calculated absolute blood flow rate may be used for the diagnosis and understanding of microvascular disease.
Accordingly, there is a need to provide alternative systems and methods for determining the absolute blood flow rate in blood vessels, such as coronary arteries.